Whatwill be the cipher text produced bythe following cipher function for the plain text ISRO with key k =7. [Consider $$'A'=0, 'B'=1, ......'Z’ = 25]$$
$$C_{k}(M)=(kM+13)$$ mod 26.

A

RJCH

B

QIBG

C

GQPM

D

XPIN